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<head>
  <title>删除失败</title>
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  <h1>删除失败！请检查所选择的学生是否在竞赛记录表中存在相应参赛记录。</h1>
  <p>倒计时：<span id="countdown">3</span>秒后自动返回上一页...</p>
  <button onclick="goBack()">返回上一页</button>
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